linux-kernel - Re: [PATCH v4] watchdog: qcom_wdt: set WDOG_HW

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Message-ID: <5b7def39-8c23-d30f-e2d3-bc38beee8919@roeck-us.net>
Date:   Sun, 1 Nov 2020 21:03:34 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Kathiravan T <kathirav@...eaurora.org>,
        Robert Marko <robert.marko@...tura.hr>, agross@...nel.org,
        bjorn.andersson@...aro.org, wim@...ux-watchdog.org,
        linux-arm-msm@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Luka Perkov <luka.perkov@...tura.hr>
Subject: Re: [PATCH v4] watchdog: qcom_wdt: set WDOG_HW_RUNNING bit when
 appropriate

On 11/1/20 7:58 PM, Kathiravan T wrote:
> 
> On 10/31/2020 7:38 PM, Guenter Roeck wrote:
>> On 10/31/20 5:11 AM, Robert Marko wrote:
>>> If the watchdog hardware is enabled/running during boot, e.g.
>>> due to a boot loader configuring it, we must tell the
>>> watchdog framework about this fact so that it can ping the
>>> watchdog until userspace opens the device and takes over
>>> control.
>>>
>>> Do so using the WDOG_HW_RUNNING flag that exists for exactly
>>> that use-case.
>>>
>>> Signed-off-by: Robert Marko <robert.marko@...tura.hr>
>> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> 
> Thanks for addressing the comments and now the patch looks good to me. One more suggestion, can we make the initcall level of the driver to subsys_initcall_sync so that the driver gets registered immediately after the watchdog_core is registered and watchdog_core starts pinging the WDT?
> 

That would mean to replace module_platform_driver(), which would be a whole
different discussion, is not widely needed, and would potentially interfere
with the subsys_initcall_sync() in the watchdog core. This will require
specific evidence that a problem is seen in the field, and that it is truly
needed. Plus, it would have to be a different patch (which you could submit
yourself, with evidence). Let's stick with one logical change per patch,
please.

Guenter